Ernst Heinrich Philipp August Haeckel was born 1834 in Potsdam, but grew up in Merseburg, just outside of Leipzig. His father was a lawyer and worked for the government. After studying at Würtzburg, in 1857 he obtained a medical degree from the University of Berlin under pressure from his family. His own interests were towards Botany and, through his professor Johannes Müller (1801-1858), Zoology. Müller was an anatomist and physiologist, and it was with him that Haeckel did field work, observing small sea creatures on the north German coast. Haeckel opened his medical practice, but he was not enthusiastic about it.

Reading Darwin’s Origin of the Species by Means of Natural Selectionwas an important event in his life. He went back to school in Jena, studying under Carl Gegenbauer and then became professor of comparative anatomy there in 1862. Haeckel’s early scientific work was in the area of invertebrates. Well regarded to this day for his fieldwork, he named thousands of new species from 1859 to 1887. It was out of this work that Haeckel developed a number of the ideas for which he is known, including his law of recapitulation: ontology recapitulates phylogeny1. This thesis is also known as the Biogenetic Law, and states that the development of an embryo and the stages of growth of the young of a species repeat the evolutionary development of that species. Haeckel was quite quotable, and has left as a legacy to biology such words as phylum, phylogeny and ecology – “oekologie” which he created from the Greek root oikos to refer to the relationship of an animal to its organic and inorganic environment.

Haeckel was deeply impressed with Darwin's Origin of the Species by Means of Natural Selection. While he deprecated the idea of natural selection as the mechanism of evolution, he was enthusiastic about the concept of biological evolution itself. In his 1862 monograph on Radiolaria he placed Darwin's concept in a central role, and in his 1866 book General Morphologyhe attempted to work out the practical implications of evolutionary theory in a general way. Haeckel's General Morphology did not sell very well, so Haeckel rewrote the concepts in a more popular form and published the results in an 1868 book called The Natural History Of Creation (Natürliche Schöpfungsgeschichte). This along with an active lecturing and writing career led him to become the leading proponent of evolution in German-speaking countries. It is important to note that although Haeckel was a proponent of Evolution, he was not technically a Darwinian because he did not believe that natural selection was the method by which evolution progressed. This deprecation of the concept of natural selection as the mechanism of forward progress of evolution Haeckel had in common with Rudolf Steiner, another strong proponent of evolution, although of a more spiritual kind.2 Haeckel's view was more in the tradition of Lamarck; he felt that environmental influences acted upon organisms to create differentiation.

Haeckel's efforts on behalf of evolution went well beyond merely scientific endeavors. He wrote profusely on many non-scientific subjects. While still considered quite competent as an invertebrate anatomist, most of his speculative writings have come to be regarded as mistaken. These speculative writings branch out into areas such as anthropology, psychology (which he proposed be considered a branch of physiology), ethics, theology, politics, and cosmology. His was a systematic and synthesizing mind and he was unafraid to go boldly where the evidence would barely support him. One area of speculation was how organic matter arose from inorganic matter, or the origin of life. Having studied the rather crystalline Radiolaria, Haeckel arrived at the conclusion that a process of crystallization had produced organic life forms from inorganic matter in a spontaneous process. He posited the existence of a “monera” or protoplasm without nuclei, as the common ancestor of all organic life forms. Evidence of such a creature has not yet been found, and most biologists doubt it ever will be.

This courage to fill gaps in scientific knowledge with intuitions was typical of Haeckel. He was the first to attempt a systematic genealogical tree showing the evolution of higher life forms from lower ones, filling in the gaps where necessary. He perfected and elaborated his genealogical tree over decades. While some particulars have changed from Haeckel's time, his basic outline remains essentially intact, and the concept of an evolutionary tree is central to modern biology.

Haeckel's popular presentation of evolution in German-speaking countries and his eminently quotable prose led him to become a nineteenth-century celebrity. He appeared to enjoy this role greatly, and seemed encouraged by this to take on the greater philosophical questions, as well as rattle the chains of old church dogma with great enthusiasm. His speculative writings saw a culmination in his 1899 book The Riddle Of The Universe(Die Welträtzel). In this book he elaborated a comprehensive philosophical system based upon his biological and evolutionary findings. Here he contemplated the philosophical implications and theological consequences of organic evolution. Ultimately he saw not qualitative but only quantitative differences between self-conscious human beings and other highly evolved mammals. His was a philosophy of Monism - namely a belief that the universe is ultimately a differentiation of a single type of substance.3

Haeckel’s work was very influential in his lifetime and for some time thereafter. His efforts were a significant factor in the wider acceptance of the theory of evolution in central Europe, and his more philosophical works were a subject of much debate in intellectual circles for decades. Parts of his philosophical works show the influence of the negative traits of his time period, and these in particular were exploited by admiring national socialists. In Haeckel they found justifications for a eugenic policy is based on Social Darwinism, for racism, and for nationalism. Haeckel's quote "politics is applied biology" was taken to its logical conclusion under Hitler.

Creationists have found Haeckel a favorite target because of errors both small and large in the various parts of his scientific work.

While Haeckel's "law of recapitulation" (ontology recapitulates phylogeny) has been boldly declared disproved for much of the 20th century, a comprehensive understanding, as usual, shows that such a statement is overly simple. An unsigned presentation on the University of California at Berkeley's Evolution website revisited the idea recently:

“The 'law of recapitulation' has been discredited since the beginning of the twentieth century. Experimental morphologists and biologists have shown that there is not a one-to-one correspondence between phylogeny and ontogeny. Although a strong form of recapitulation is not correct, phylogeny and ontogeny are intertwined, and many biologists are beginning to both explore and understand the basis for this connection.”4

1. From Ernst Haeckel. Riddle of the Universe at the Close of the Nineteenth Century. 1899. as cited in “Haeckel, Ernst Heinrich." Encyclopedia Britannica. 1911. 1911Encyclopaedia.org. 24 Jan. 2004. <http://46.1911encyclopedia.org/H/HA/HAECKEL.htm >
"I established the opposite view, that this history of the embryo (ontogeny) must be completed by a second, equally valuable, and closely connected branch of thought - the history of race (phylogeny). Both of these branches of evolutionary science, are, in my opinion, in the closest causal connection; this arises from the reciprocal action of the laws of heredity and adaptation... 'ontogenesis is a brief and rapid recapitulation of phylogenesis, determined by the physiological functions of heredity (generation) and adaptation (maintenance).'"

2. See Rudolf Steiner. The Theory of Knowledge Implicit in Goethe's World Conception. GA2, Chapter 1, part 16 for a full discussion of adaptation and natural selection from Steiner's perspective.

3. As a philosophy, Monism stands in obvious opposition to Dualism. Whereas Dualists see a fundamental differentiation between mind and body, the simple forms of Monism claim that the world is entirely one thing, either material, in which case it is called Philosophical Materialism, or that is entirely mental or spiritual, called Philosophical Idealism.